Vibrator



Feb. 18, 1936.

G. B. PICKOP VIBRATOR Filed Jan. 29, 1935 2 6g/g3. KTS I A2Z /0 24 Z5 @IZ A 1 Irlllllllrln 'l Half?? Patented Feb. 18, 1936 UITED STATES PATENTFFICE 11 Claims.

This invention relates to vibrators and more especially to that class ofsuch tools wherein a piston is reciprocated in a cylinder by means of afluid under pressure, such as compressed air, for example. I have shownmy invention applied to such a reciprocating compressed air vibrator asis commonly employed in foundries in connection with loosening patternsor pattern plates, or rapping flasks in order to remove castings orpatterns from molds.

It has been quite common in the past to employ in such vibrators aspring which is mounted at one end of the cylinder and acts upon thepiston to urge it against the opposite end of the cylinder when thefluid pressure is shut oi and the piston comes to rest. It is, in theordinary form of vibrator, necessary to have the piston come' to rest atone end of the cylinder in order that it may start when the air pressureis turned on. The reason for this is that when the compressed air isshut off during the operation of the ordinary vibrator, there will ofcourse be a certain amount of compressed air left in the inlet tubewhich must exhaust itself, so that the piston will not necessarily stopinstantaneously at the position occupied when the air is shut off.

As a result, the piston starts in its travel over another stroke andusually reaches a point midway between the ends of the cylinder whereinthe air coming in through the intake passage is permitted to leak by toenter both ends of the cylinder, and at the same time the exhaust portsare slightly opened to a sufficient extent to per- -mit leakage of thisair from the cylinder, and it is in this position that the piston islikely to stop. If the air is again turned on, the piston will be in abalanced condition, as some of the air will leak by into both ends, andlikewise leak out of both exhaust ports, and hence the operation of thevibrator will not start.

The present invention has for one of its objects the provision of avibrator with which it will be unnecessary to employ a spring and whichwill be so constructed that the piston will always stop in a positionfrom which it will readily start when the pressure fluid is againsupplied.

Another object of the invention is the provision of a springlessself-starting vibratory tool of the cylinder and piston type which willbe simple in construction, economical to manufacture, and positive inits operation.

Still another object of the invention is to provide a very simple formof vibrator of the piston and cylinder type which will be so constructed'that the piston will stop in a position to be moved by the mechanicalimpact of the entering compressed fluid.

To these and other ends, the invention consists in the novel featuresand combinations of parts Ato be hereinafter described and claimed. v5

In the drawing:

Fig. 1 is a top plan View of a vibrator embodying my invention;

Fig. 2 is a sectional View of the vibrator showing the piston in theposition which it will u'su- 10 ally occupy when in repose;

Fig. 3 is a view similar to Fig. 2 but Showing the parts in anotherposition with the piston at one end of its stroke;

Fig. 4 is a sectional view on line lI--II of Fig. 15 2; and

Fig. 5 is a View of the piston member alone.

The tool which I have chosen to illustrate and describe as a preferredembodiment of my invention comprises a casing IIl bored out to pro- 20vide a cylinder II, the ends of which are closed by the heads I2 and I3,which, as shown, may be threadedly secured to the vibrator body orcasing I0. Within the cylinder, a reciprocatory piston I4 is disclosedwhich, as will be more fully explained hereinafter, is designed yto beoperated by a fluid under pressure, such as compressed air, for example,so that it will be reciprocated in a back-and-forth movement to strikeagainst the heads I 2 and I3 to set up vibra- 30 tions in the casingIll, and through the attaching member I5 provided upon one of the endheads, vibrate the object I6 to which the member I5 is secured by thebolt I1.

The body or casing Iil is provided atits central 35 portion with a bossI8 having a threaded bore I9 communicating through a port 20 with thecylinder or chamber II. It will be understood that the hose or pipeline, or other device carrying the pressure fluid to operate the tool,will be 40 secured to the boss I8, the port 20 being the intake openingto admit pressure fluid to the cylinder II of the tool.

Upon each side of the boss I8, a single longitudinal bore is provided inthe body of the casing 45 I0 extending parallel to the axis of thecylinder. These bores or passages are designated by the numerals 2l and22 and each is connected with the cylinder by ports 23 and 24, whichportslie relatively closely to the intake opening 20. The 50 passages 2land l22 also communicate with the cylinder adjacent the ends of thelatter by the ports 25 and 26.

The piston I4, shown more particularly in Fig.

5, is provided with a relatively reduced central -55 portion and endportions also reduced in diameter, leaving the intermediate portions 21and 28 relatively enlarged so as to fit fairly closely the interior ofthe piston. Between the portions 21 and 28, the piston, as stated, isreduced in diameter to provide a relatively wide peripheral grooveterminating at its ends in the shoulders 29 and 30 adjacent the portions21 and 28.

The bottom 3| of a portion of this groove, that portion adjacent thepart 21, as shown, is substantially parallel to the axis of the piston,while the bottom 32 of the remainder of this groove is inclined towardthe axis of the piston, so that the shoulder 3i) is relatively wide aswell as being abrupt. The part 3| joins the part 32 on a line which isslightly nearer the right-hand end ofY the piston than the left-handend.

It will be apparent that when the piston is at one end of its stroke,the left-hand end, as shown in Fig. 3, for example, compressed airentering through the bore I9 and port 2D is permitted to enter thecylinder in the space between the shoulders 29 and 3l] of the piston.This air can then pass into the passage 22 through the port 24, as thelatter port will be uncovered by the part 28 lof the piston. The airthen passes downwardly through the port 26 into the end of the pistonand drives the latter to the right. When the piston reaches theright-hand position, an exhaust port will be uncovered, as will behereinafter explained, and the left-hand end of the cylinder will bepermitted to exhaust.

The body I0 is provided with exhaust openings 33 and 34. It will benoted that the exhaust opening 34 is slightly smaller than the exhaustopening 33 and is also slightly farther from the end of the cylinder.For instance, if the center of the exhaust port 33 is l--ths inches fromthe end of the cylinder, I position the center of the opening 34 at adistance of two inches from the end of the cylinder, so, as will beunderstood, the piston must travel further toward the left to uncoverthe exhaust port 34 than it must travel toward the right to uncover theexhaust port 33. The result will be a slight unevenness in the energy ofthe blows imparted upon the ends vof the tool as there will be a morenearly complete venting or exhausting of the left-hand end of thecylinder than there will be of the righthand end of the cylinder.However, it is this unequal positioning of the exhaust openings inconnection with the particular shape of the central part of the pistonthat enables me to provide a satisfactory springless vibratory tool ofthis character.

The operation of the device while in use is readily understood as theexhaust ports 33 and 34 function in the usual way, and it has alreadybeen explained that compressed air entering the port 20 will be carriedto one end or the other of theicylinder by the passages 2| or 22,depending upon the position of the piston. It will, however, probably behelpful to explain the starting and stopping of the vibrator piston.When .the supply of compressed air is shut olf from the Vibrator, thepiston being, for example, at one tend of the cylinder, as shown in Fig.3, the compressed air remaining in the pipe and in the passages of thevibrator as well as in the left-hand end of the cylinder or chamber l lwill tend to move the piston toward the right as the port 34 isuncovered and the right-hand end of the cylinder is vented. Thismovement to the right will continue until the piston reaches theposition shown substantially in Fig. 2 wherein the exhaust port 33 hasbeen opened to a sufficient extent to permit a slight amount of air toleak by. As the exhaust port 34 is slightly closer to the center of thevibrator body or at a greater distance from the right-hand end, thisexhaust opening will be closed and the piston at the same time will beslightly nearer the left-hand end of the cylinder than the right,whereby the port 23 will be closed but the port 24 will be opened to aslight extent to permit a slight leakage of air into the passage 22. Inthis position there will be a balanced condition between the parts andit is found that this is the position at which the piston comes to restwhen it does come to rest adjacent the center of the cylinder. It is ofcourse apparent that if it should come to rest at either end of thecylinder, no diiculty will be encountered in its starting when the airis turned on.'

If, with the parts in the position shown in Fig. 2, the compressed airis turned on, there will of course be a sudden rush of air through theport 2S as the air within the cylinder adjacent this port and betweenthe shoulders 29 and 33 of the piston has leaked out through the passage22 and exhaust 33. This column of air will pass down the inclinedsurface 32 and strike against the abrupt shoulder 3E! and exert amechanical push to move the piston to the right. This immediately movesthe piston to a position in which the port 20 is uncovered and the ventport 33 closed so that the air passes to the left-hand end of the pistonand immediately places it in operation.

While I have shown and described a preferred embodiment of my invention,it will be understood that it is not to be limited to all of the detailsshown, but is capable of modification and -variation within the spiritof the invention and within the scope of the appended claims.

What I claim is:

1. A vibratory engine or tool comprising a body provided with a cylinderand a piston mounted to reciprocate in the cylinder, said body being.provided with an inlet opening adjacent its central portion leadinginto the cylinder and also being provided with passages eachcommunicating with the cylinder adjacent an intermediate portion thereofand adjacent one end thereof, the piston being vprovided with a recessadjacent its central portion adapted to effect communication betweensaid inlet port and one or the other of said passages, and said recesshaving an inclined bottom surface terminating in an abrupt shoulder.

2. A vibratory engine or tool comprising a body provided with a cylinderand a piston mounted to reciprocate in the cylinder, said body beingprovided with an inlet opening adjacent its central portion leading intothe cylinder and also being provided with passages each communicatingwith vthe cylinder, said body being provided with an inlet openingadjacent its central portion leading into the cylinder and also beingprovided with passages each communicating with the cylinder iii)adjacent an intermediate portion thereof and adjacent one end thereof,said piston being provided with a relatively wide annular grooveintermediate its ends adapted to effect communication between said inletport and one or the other of said passages, and said groove being deeperadjacent one end than the other and terminating at the deeper end in arelatively wide abrupt shoulder.

4. A vibrator comprising a body provided with a cylinder and a pistonmounted to reciprocate in the cylinder, said body being provided with aninlet opening adjacent its central portion leading into the cylinder andalso being provided with passages each communicating with the cylinderadjacent an intermediate portion thereof and adjacent one end thereof,the piston being provided with a recess adjacent its central portionadapted to effect communication between said inlet port and one or theother of said passages, said recess having an inclined bottom surfaceterminating in an abrupt shoulder, said cylinder being provided Withexhaust ports adjacent the ends thereof, and one of said exhaust portsbeing at a greater distance from the end of the cylinder than the otherexhaust port.

5. A vibrator` comprising a body provided with a cylinder and a pistonmounted to reciprocate in the cylinder, said body being provided with aninlet opening adjacent its central portion leading into the cylinder andalso being provided with passages each communicating with the cylinderadjacent an intermediate portion thereof and adjacent one end thereof,said piston being provided with a relatively Wide annular grooveintermediate its ends adapted to effect communication between said inletport and one or the other of said passages, said groove being deeperadjacent one end than the other and terrninating at the deeper end in arelatively wide abrupt shoulder, said body being provided with exhaustports adjacent the ends thereof, and the exhaust port at that end of thebody nearer said abrupt shoulder being nearer to the end of the casingthan the other exhaust port.

6. A vibrator comprising a casing provided with a cylinder and a pistonmounted to reciprocate in the cylinder, said casing being provided withexhaust ports adjacent the ends thereof and an inlet port adjacent itscentral portion, said piston being provided with a peripheral groovecommunicating with said inlet port, said casing being provided withpassages to provide communication between said groove and the ends ofthe cylinder, said groovebeing deeper at one end than at the other toprovide a relatively wide abrupt shoulder at the deeper end, and one ofsaid exhaust ports being nearer the end of the cylinder than the other.

'1. A vibrator comprising a casing provided with a cylinder and a pistonmountedto reciprocate in the cylinder, said casing being provided withexhaust ports adjacent the ends thereof and an inlet port adjacent itscentral portion, said piston being provided with a peripheral groovecommunicating with said inlet port, said c-asing being provided withpassages to provide communication between said groove and the ends oftheV cylinder said groove being deeper at one end than at the other toprovide a relatively wide abrupt shoulder at the deeper end, and one ofsaid exhaust ports being nearer the end of the cylinder than the other,the said one exhaust port also being at that end of the casing adjacentsaid relatively wide shoulder on the piston.

8. A vibrator comprising a casing having a cylinder and a piston mountedtol reciprocate in said cylinder, said casing having an air inlet portand means for delivering air entering said inlet port tol the ends ofsaid cylinder, means effecting the stopping of said piston in a positionfrom which it will be driven to one end of the cylinder when the motivefluid is turned on, said means including an exhaust port adjacent eachend of the cylinder, one of said exhaust ports being nearer the end ofthe cylinder than the other, said piston having portions thereon closingsaid exhaust ports, and said portions terminating in planessubstantially equidistant from the center of the piston.

9. A vibrator comprising a casing having a cylinder and a piston mountedto reciprocate in said cylinder, said casing having an air inlet portand means for delivering air entering said inlet port to the ends ofsaid cylinder, means effecting the stopping of said piston in a positionfrom Which it Will be driven to one end of the cylinder when the motivefluid is turned on, said means including an exhaust port adjacent eacnend of the cylinder, one of said exhaust ports being nearer the end ofthe cylinder than the other, and said piston being provided with ashoulder to receive, when in a position of rest, a mechanical impactfrom the pressure fluid When the latter is turned on.

l0. A fluid pressure vibrator comprising a casing provided with acylinder and a piston mounted to reciprocate therein, said piston havingan annular :groove in its surface. at a point intermediate its ends,there being an abrupt face at one end only of said groove, the casingbeing provided with an air inlet port in constant communication withsaid groove, and means for establishing intermittent communicationbetween said port and the cylinder at one end o-f the piston.

11. A fluid pressure vibrator comprising a casing provided with acylinder and a piston mounted to reciprocate therein, said piston havingan annular groove in its surface at a point intermediate its ends, therebeing an abrupt face at one end only of said groove, and said groovehaving an inclined bottom surface extending from said face toward thesurface of the piston, the casing being provided with an air inlet portin constant communication with said groove, and means for establishingintermittent communication between said port and the cylinder at one endportion thereof.

GEORGE B. PICKOP.

